Story: Rabbits

Page 1 – The spread of rabbits in New Zealand

Rabbit behaviour and habitat

The common European rabbit (Oryctolagus
cuniculus) is native to Spain and Portugal, and has
adapted to that region’s unpredictable Mediterranean climate.
Rabbits are able to take advantage of good seasons and breed
prolifically when food is available. They can also survive
through extended droughts – even eating their faeces to
absorb more nutrients. Rabbits are particularly well adapted
to the drier parts of New Zealand, where survival rates of
the young are high.

Rabbit or hare?

Hares and rabbits are lagomorphs and belong to the
Leporidae family. Hares are generally bigger than
rabbits. They have longer, black-tipped ears and live
solitary lives. Rabbits live in social groups. Their young
are born blind and without fur, and spend the first few
days of their lives in a fur-lined nest, whereas baby hares
can run within a few minutes of birth. Hares are a nuisance
in some parts of New Zealand, but do not damage vegetation
the way rabbits do.

Introducing rabbits to New Zealand

Rabbits were brought to New Zealand and released for both
food and sport at various sites as early as the 1830s.

Rabbit plagues

Once rabbits became established, their population
increased to plague proportions several times. The first
rabbit plague began in the early 1870s and petered out about
1895. Another increase occurred in the early 1920s. There was
a major irruption in the 1940s, and the most recent began in
the late 1980s.

Impact of rabbit plagues

Rabbits have cost New Zealand many millions of dollars,
through the direct cost of controlling them, and the loss of
production from farms. Their impact on the drier areas of the
South Island has been little short of an ecological disaster,
as the vegetation grazed off by rabbits has never recovered.
The worst affected areas – once well covered with tussock,
grasses and small shrubs – now have very little vegetation
cover, which has led to soil erosion by wind and rain. The
loss of soil has left areas where only the hardiest
colonising plants will now grow. Burrowing by rabbits in some
soil types and on steep slopes has also led to soil
erosion.

The South Island plague

Southland and Otago

A population of rabbits became established in the coastal
sandhills between Invercargill and Riverton in the 1860s. In
the early 1870s rabbits from this area began moving up the
banks of the nearby rivers onto the inland plains. By 1875
they were established in Central Otago. By the early 1880s
rabbits had spread to all parts of Otago and Southland and
had begun to invade Canterbury. In the 1890s they overran the
Mackenzie Country.

Marlborough

Rabbits were released inland from Blenheim in 1858 and
again in 1865. In the early 1870s they spread up the Wairau
and Awatere rivers into inland Marlborough. At the same time,
silver-grey rabbits that had been released near Kaikōura
about 1862 moved into the drier inland areas. By about 1887
both of these populations began encroaching on the Amuri
district in North Canterbury.

Breeding like rabbits

A single female rabbit can have 45 offspring in a year,
producing a litter of four or five kittens every six weeks.
Rabbits can breed at five months of age, so a female born
in early spring will produce young within the same breeding
season. Rabbit populations commonly increase eight- to
tenfold in one season.

South Island plague peak

In the South Island the first rabbit plague had peaked by
1895. After this, rabbit numbers remained high in the
semi-arid region of Central Otago, but dropped markedly in
other areas. Most of central Canterbury remained relatively
free of the pest. However, in later rabbit irruptions the
region did not escape so lightly.

The spread of rabbits in the North Island

The timing and dynamics of the rabbit plague in the North
Island differed from the South Island. The extensive areas of
forest and higher rainfall hindered their spread.

Rabbits were established in the Wairarapa by 1863, but an
outbreak of coccidiosis (a parasitic intestinal disease) in
the 1880s slowed their spread. However, by the beginning of
the 20th century, large numbers had spread into Hawke’s Bay.
They did not reach Taranaki and the far north in any number
until about 1946.

In the North Island, rabbits have only been a major
problem in Hawke’s Bay and parts of Wairarapa.